SAN FRANCISCO -- San Francisco Mayor Gavin Newsom, responding to a Chronicle investigation of troubling delays in the city's 911 system, ordered top city officials on Monday to recruit and retain more emergency dispatchers and to regularly review all medical cases in which the city failed to meet its response standard.

Under the order, which was effective immediately, Newsom also set deadlines for completing initiatives to reduce response times in life-threatening emergencies, including using Global Positioning System technology to better track ambulances and fire engines and stationing more emergency vehicles in busy intersections of the city.

The order came in response to stories in The Chronicle on Sunday and Monday that detailed problems in the city's 911 medical response system. In an analysis of high-priority emergency medical calls, the newspaper found that at least 439 people have died in the city since 2004 while waiting for an ambulance or after delayed medical help arrived.

The analysis examined dispatch logs for about 200,000 Code 3 and Echo calls and found that in 27 percent of the calls, the first responders arrived later than the city's goal to get help to the scene within 6 1/2 minutes in 90 percent of those calls.

"The mayor is committed to making sure that our 911 system is second to none," said Nathan Ballard, Newsom's spokesman. "When you call 911, you deserve a quick response, no matter where you live in the city."

In a new move, Newsom directed the city's Human Resources Department to work closely with Department of Emergency Management to recruit and retain dispatchers. City officials and emergency experts had told The Chronicle that San Francisco's 911 call center suffers from chronic shortages of dispatchers.

Newsom directed the department to recruit more multilingual staff and review the current system for answering calls from people who do not speak English.

The mayor also demanded that within 60 days, the heads of the three city departments that oversee the emergency medical system submit a report with recommendations for improving response times. The city currently gets help to the scene in about 8 minutes or less in 90 percent of high-priority medical calls.

Newsom ordered the heads of those departments - the Department of Emergency Management, the Department of Public Health and the Fire Department - to meet four times a year to review all instances of delayed medical responses.

Vicki Hennessy, the interim executive director of the Department of Emergency Management, said she believed the staff could meet all the mayor's demands. She acknowledged, however, that recruiting new dispatchers has been challenging.

"That's something we still need to work harder on, and we will work harder on it," Hennessy said.

The directive also gives the Department of Emergency Management 60 days to fully shift to a computer-based system for evaluating callers' symptoms and to complete a program that stations ambulances throughout the city instead of at firehouses.

Newsom told the city's Committee on Information Technology, which makes recommendations for new technology purchases, to make it a priority to buy equipment that pinpoints the locations of ambulances in the field.

"Hopefully, we'll have a positive reduction in overall response time. We're definitely headed in that direction," said Hayes-White, who noted that 31 emergency medical workers are set to graduate next month and will staff the roving ambulances.

The Chronicle analysis also found that emergency crews were most often late in responding to calls from the south and southeastern portions of the city.

Supervisor Gerardo Sandoval said he was not surprised that the district he represents had the most late responses, at 38 percent.

"Nothing has really changed," Sandoval said. "The southeast portion of the city still gets the worst services, and there's no excuse for it."